The present invention relates generally to thermostatic water mixing valves, and specifically to such valves internally configured to provide an improved mixing chamber from which water passes around a thermostatic expansion element to enhance output temperature stability.
Thermostatic valves which mix hot and cold water in varying proportions to supply water of a preset nominal temperature are well known. A common design for such valves incorporates two valve devices whose closure members are coordinately controlled by a thermostatic expansion element. The valve devices control admission of cold and hot water into a mixing chamber from which mixed cold and hot water flows past the thermostatic expansion element.
In known designs for valves of this type, the outlet water temperature is generally sensitive to the cold and hot water inlet pressures. Thus, the preset outlet temperature is accurately maintained only if the supply pressures of the cold and hot water are constant. Conversely, operation of an ideal mixing valve should be characterized by an outlet temperature that is independent of inlet pressures.
The foregoing problem is addressed in published German patent document DE 44 23 240 C1, which discloses a mixing valve having a baffle plate within its mixing zone. The present invention is directed to a design that further improves the outlet temperature response characteristics of a thermostatic mixing valve.